Browsing by Author "N�sser, Marcus"

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    Heterogeneity in glacier thinning and slowdown of ice movement in the Garhwal Himalaya, India
    (Elsevier B.V., 2023-03-05T00:00:00) Bhambri, Rakesh; Schmidt, Susanne; Chand, Pritam; N�sser, Marcus; Haritashya, Umesh; Sain, Kalachand; Tiwari, Sameer K.; Yadav, Jairam Singh
    Limited ground-based surveys and extensive remote sensing analyses have confirmed glacier thinning in the Garhwal Himalaya. More detailed studies on specific glaciers and the drivers of reported changes are essential to comprehend small-scale differences in the effects of climatic warming on Himalayan glaciers. We computed elevation changes and surface flow distribution for 205 (?0.1 km2) glaciers in the Alaknanda, Bhagirathi, and Mandakini basins, all located in the Garhwal Himalaya, India. This study also investigates a detailed integrated analysis of elevation changes and surface flow velocities for 23 glaciers with varying characteristics to understand the impact of ice thickness loss on overall glacier dynamics. We observed significant heterogeneity in glacier thinning and surface flow velocity patterns using temporal DEMs and optical satellite images with ground-based verification. The average thinning rate was found to be 0.07 � 0.09 m a-1 from 2000 to 2015, and it increased to 0.31 � 0.19 m a-1 from 2015 to 2020, with pronounced differences between individual glaciers. Between 2000 and 2015, Gangotri Glacier thinned nearly twice as much as the neighbouring Chorabari and Companion glaciers, which have thicker supraglacial debris that protects the beneath ice from melting. The transitional zone between debris-covered and clean ice glaciers showed substantial flow during the observation period. However, the lower reaches of their debris-covered terminus areas are almost stagnant. These glaciers experienced a significant slowdown (~25 %) between 1993�1994 and 2020�2021, and only the Gangotri Glacier was active even in its terminus region during most observational periods. The decreasing surface gradient reduces the driving stress and causes slow-down surface flow velocities and an increase in stagnant ice. Surface lowering of these glaciers may have substantial long-term impacts on downstream communities and lowland populations, including more frequent cryospheric hazards, which may threaten future water and livelihood security. � 2023 Elsevier B.V.
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    Reassessing the Karakoram Through Historical Archives
    (Springer International Publishing, 2022-11-11T00:00:00) Bhambri, Rakesh; Chand, Pritam; N�sser, Marcus; Kawishwar, Prashant; Kumar, Amit; Gupta, Anil K.; Verma, Akshaya; Tiwari, Sameer K.
    The Karakoram region is an integral part of the Hindu Kush�Karakoram�Himalaya (HKH) mountain system and forms the great divide between the drainage of the Indus and Tarim basins. This region has a substantial geographical, historical, economical, cultural, and geopolitical importance owing to its location, rugged topography, distinct climate regime, and the presence of numerous glaciers. It acts as a water tower where its unique assemblage paved the way for developing ancient trade routes facilitating cultural exchange between Central Asia and the Indian subcontinent. It has attracted a large number of expeditions and scientific studies for more than 200 years, bringing significant advances in geographical knowledge. However, the spatial extent of the Karakoram in many studies particularly during the 2010s exhibits a large inconsistency. We, therefore, complied ?100 maps and vast literature to present the evolution of the geographical term �the Karakoram� and its spatial extent based on historical archives. We also provide a digital outline of the Karakoram region using GIS tools based on descriptive enumerations of the Royal Geographical Society (RGS) and the Survey of India (SoI) which we hope will provide new insight for a wide range of scientific disciplines, including geography, glaciology, geology, history, and cartography. � The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.